This invention concerns filtration apparatus of a type used in industrial operations to remove contaminants from a liquid used during manufacturing. After machining such parts as engine blocks, manifolds, it is usual to wash the parts to remove chips, grinding swarf, cutting fluid residue, etc. The parts are conveyed through an enclosed washer chamber where spray jets wash off these contaminants, with the spray liquid and washed off material collected in a tank beneath the washer chamber.
It is necessary to remove the chips and other debris from the liquid to allow continued reuse of the liquid in the washing sprays, and in the past, an inclined filter media belt filter was mounted within the tank, periodically indexed to remove accumulated filtrate, the liquid drawn through the filter media belt to be filtered. A drag conveyor is also periodically indexed to convey accumulated solids out of the tank for disposal. See U.S. Pat. No. 6,042,726 for an example of such a filter.
In this arrangement, the filter apparatus is difficult to service, as the belts and conveyor are enclosed within the washer collector tank.
In some versions, the feeding of disposable media over the belt to remove fine particles would require access to the rear of the tank, which is often difficult in many installations.
To pump the contaminated liquid to an external filter would require a separate tank to receive the liquid in order to allow belt indexing, increasing the floor space and cost of the equipment required.
This situation is also presented with other stand alone equipment such as individual grinders and other machine tools having a dedicated chip cutting fluid collection tanks below the machining zone.
It is the object of the present invention to provide a filter apparatus for removing contaminants received in a tank such as a washer collection tank or other equipment, which apparatus is not necessary to be disposed within the tank and does not itself require a separate collection tank and which can quickly carry out the periodic indexing of a filter media belt to clean solids therefrom.
The above recited object, and others which will be understood upon a reading of the following specification and claims are achieved by a filter apparatus mounted above a clean tank. A downwardly facing upper pan is movable relative a floor pan to bring a perimeter flange into engagement with a hose seal disposed on the lower pan to create a sealed filter chamber. A vacuum box is mounted below the lower floor pan and connected to the clean tank by a piping connection to transfer fluid to a clean tank, the piping extending out from one side of the vacuum box, down to the level of the clean tank and back into one side of the clean tank. The piping connection has a main control valve located along the length of the fluid connection.
A pump is connected to the clean tank for pumping filtered liquid back to the utilizing equipment, which pumping generates a negative pressure in the clean tank (and also the vacuum box).
A filter belt loop has an upper segment extending into the filter chamber over one segment of the hose seal which extends entirely around the filter chamber and onto a perforated plate supported on a set of elongated bars fixed on the lower pan, and out of the filter chamber over another segment of the hose seal.
A vacuum pump is provided to evacuate air from the tank to prime liquid flow drawn into an inlet pipe connected to the upper pan and extending into the collecting tank containing the liquid to be filtered. Upon opening of the control valve, liquid is drawn into the vacuum chamber, passing through the filter belt and into the vacuum box and thence into the clean tank.
To index the belt to clean accumulated solids, a vacuum breaker valve is opened to allow air into the filter chamber to relieve the vacuum, and drain the dirty liquid from the filter chamber. The main control valve is thereafter closed. A power cylinder lifts the upper pan from the hose seal to allow the filter media belt to be advanced to carry the belt segment on which the solids have accumulated out of the chamber to be discharged.
The recirculation pump continues to be operated during indexing to insure an uninterrupted supply of clean liquid and to maintain a vacuum in the clean tank. The vacuum level increases during pumping to a predetermined maximum level, with an air bleed vacuum control device introducing air into the clean tank when the maximum vacuum is reached to prevent an excessive vacuum level from developing which could interfere with the pumping of clean liquid out of the tank.
Upon reopening the main control valve, liquid to be filtered is again quickly drawn into the vacuum chamber, through the filter belt and into the clean tank via the vacuum box.
The vacuum pump is operated as necessary to eliminate excess air until a predetermined liquid level is restored in the tank sensed by a liquid level switch.